His old setup uses fluorescent light fixtures with T12 bulbs. These are rather bulky and inefficient bulbs. Many folks, ourselves included, would think of LED as a logical replacement. [Ben] started by looking into the various high-intensity LED modules that are available. He grabbed a catalog and started doing a couple of different calculations to compare Lumens/dollar for the upfront cost, and Lumens/Watt for the operational costs. Hands down, newer fluorescent bulbs come in cheaper on both counts and provide a wider spectrum of light.

The next decision was between purchasing the newer T5 bulbs which are rated at very high efficiencies, or to go with T8 bulbs which are better than the T12 standard but can use the same fixtures. After doing some digging he found that T5 is not much more efficient than T8, but they use an electronic ballast to boost efficiency. He ended up replacing his old magnetic ballasts with electronic ones to get high T8 efficiency at a cost that was lower than buying new T5 fixtures.

28 thoughts on “Shop lighting: weighing cost and efficiency”

I did some looking into efficiency and lifetime for fluorescent tubes a couple of years ago. Something that I noticed is that Philips only gave longevity figures for 8 hours of operation per day, turning on and off only once per day.
My suspicion is that power cycles dramatically decrease the life of these lights. In certain situations (bathroom lights, break-room lights) is it better to have LED or even incandescent, considering the degree to which long life is important to the cost-effectiveness of fluorescent?
If anyone has further insight or info, I would love to check it out.

What Ben neglected to consider in his comparison is reflector efficiency and restrike. No matter how much light is produced, it’s useless unless it reaches its destination.

T5’s can use mirrored reflectors that reflect light more efficiently than white surfaces. They also have optimized shapes, which direct light that bounces off the reflector around the bulbs, thus minimizing restrike (light lost due to hitting the bulb).

T8’s could also use mirrored reflectors, but due to the wider bulb, the reflectors would also have to be scaled up proportionally to a size which is considered impractical for most fixtures. So instead we see only the simple, white, inefficient reflectors in commercial products. (Although there is potential for making DIY T8 reflectors if you’re so inclined, I’ve toyed with the idea of building scaled up T5 designs inexpensively with cardboard and mylar.)

So while T5’s are not significantly more efficient by themselves, the reflectors they can be paired with make them much more efficient in practice. Good reflectors will set you back some money, but the energy savings will pay for them in due time. *Especially* if you air condition the lighted area, because more efficient lighting means you need less wattage, so there’s less heat the AC just has to pump back out of the room. Here in the Deep South that’s a nice double-whammy.

Of course, LEDs need no reflectors and have zero restrike, so they an even bigger efficiency bonus in practice that you will not see by comparing numbers in a catalog. Although their initial expense and spectrum leave something to be desired, as Ben correctly noted. In my opinion it’s wise to hold off on them for a few years longer and see how they develop.

I replaced the fluorescent lights on the stairs of my building with LEDs. The light is acceptable even if the plastic of fixture absorb much light. My neighbors are happy and it’s possible to change color and start a light game with a simple IR remote. What fluorescent light can do the same ?

leds and modern fluorescents are very comparable when it comes to lumen/watt. leds are more easily dimmable but commercial fixtures are often under-powered and not sufficiently cooled.
the efficiency and lifetime in the datasheets are given for 70F, at higher temperature both is significantly less, a 90+ lumen/watt led might only give you 80. trying to design them as light bulbs (a design optimized for minimal heat loss) makes it even worse.
i would go with leds for directional lighting, spot lights, or dimmable -and add lots of aluminum surface area. for general lighting fluorescent is the cheaper and equally efficient solution.

A service station around here had the lights on their fuel island retrofitted from fluorescents to LEDs. It looks as though at least in some cases, there’s an acceptable payback time (although odds are that there’s a fscking government subsidy in there somewhere fscking up the market signals).

Another option is to use electromagnetic induction fluorescent lamps.
They are electrode-less, making the bulb theorically everlasting. They fail only if the electronics fail.
And are very efficient too.

Take it from someone that works in the lighting industry, cheap T5 ballasts screwed to painted white 1×4 boards and $.50 sockets on bent brackets work like a charm. (Just don’t forget to add a “ground” wire below the entire length of both bulbs or else they won’t strike) In an unfinished basement, they blend rite in. The decrease in performance over ideal $100-$500 fixtures is quite acceptable if only used a few hours a day (it is a shop rite?). Just for god sake, replace all the incandescent bulbs down there.

Regarding number of re-strikes, it is a function more of the ballast than the bulb and new electronic ballasts are all pretty good. GE specks 10,000 re-strikes on their bulb/ballast combo with only nominal decrease in output. If you burn out a 20,000 hour bulb in you shop, you either need “real” lighting anyway, or need to get better about turning the lights off.

I used to do commercial lighting retrofit and service. First you need to differentiate, there are two kinds of T5. Standard output T5 and High Output T5. There is a significant difference in output.

T5HO is not necessarily more efficient, but you have much more light per tube which gives you all sorts of options. A standard 4 foot (Actually shorter, metric size) lamp is 54 watts, darned near double what a T8 is.

There is one other thing. Virtually all T5HO fixtures use programmed start ballasts that preheat the filament before igniting the lamp. Virtually all T8 ballasts are instant start ballasts where they just put high frequency voltage to the pins on the end and ignite them that way. The problem with this is if you turn your lights on and off more than one or two times a day the lamp life is significantly reduced. You will soon see black ends on the lamps and the lamps fail. Programmed start ballasts, like the ones that are on T5HO’s, eliminate this issue.

T5HO has one other feature, the lumen drop over time is less than T8 and Metal Halide. You can get about 2 years out of a T5HO lamp, 8 hours a day, before the output is getting poor.

I have used T5HO’s quite a bit at home. I have a 4 lamp F54T5HO fixture in by lab and I used to use 6 F54T5HO lamps in my 120 gallon salt water tank.

We can hack up whatever kipple around us into something that makes light. And some good work’s been done by Hackers willing to prove that the commercial manufactured shite is shite BY DESIGN.

After all, we’re often interested in building something that our grandchildren’s kids will still be using. Or at least, be so visually stunning that the grandkids will be influenced by it:} The fact of our Hacks being built to last is a bonus point multiplier..

Call that Hacking against planned failure?

@Tomasito:

Those Induction Lamps were/ARE “too good” and essentially scared the Gehenna out of several industries! Look at how much white sign neon is still alive after many decades for proof that yes, gas tube lights can last a long,long time.

The supreme shame of many mass market/commercial designs is that for a trivial percentage of difference, we could make things that truly *LAST* and work better too. Those Neon signs are proof that we used to.

I’ve contemplated digging out my notes on induction driving depleted cathode “circlines” in a Wrapped Toroid topology. Envision a Toroid coil where the “core” is a Circline lamp. My prototype
was an 8 or so inch diameter tube excited by 25W of 27 mhz RF. NOT a winner for daily use, but good as concept proof.

Not seen a T12 in the wild here for about 20 years. Thought that everyone had swapped out to T8’s by now.

Anyway, the issues I have had with cheap T8 fixtures is the ballasts just die on them. With the electricans always wanting cheaper, cheaper cheaper its not uncommon to see magnetically ballasted T8’s with starters still going in for new installations, when T5’s with controlled ballasts would easily have a repay time of under 1 year.

This sentence ” After doing some digging he found that T5 is not much more efficient than T8, but they use an electronic ballast to boost efficiency.” suggests that T8 come with conventional ballast as standard, and T5 have electronic ballast.

Around here I have all kinds of fixtures, including T5 with conventional, and T8 with electronic (instant-start and programmed). No retrofits; they came from the manufacturer like that.

I’m an electrician, and we do lighting retrofits all the time. As of right now, the T8 is so much more common place that the lamps have commodities pricing which is hard to beat. There are many different versions of T8s, (most common is a 741, but upgrading to an 841 gives you a boost in lumens.) Almost all of our retrofit jobs consist of replacing old fixtures (T12s or Metal Halide) with new T8 841 lamps. The new fixtures have a large mirrored reflector, and everyone has been extremely happy. With some rebates from the power company, retrofit payback periods are coming in at 1-2 years only. It’s a no brainer.

This light discussion needs to be separated into Bulbs, Ballasts and Lamps.

Bulbs: (Create visible light)
T12, T8 and T5 bulbs are all the same design so they should theoretically have the same efficiency. The only difference between types is the length and the diameter. Smaller bulb has less room for gas inside the bulb, and less glass for coating on the inside (Fluorescent bulbs create light by shooting electrons through gas inside the bulb, the coating on the inside makes the light visible, different coatings give different “color” of light). Since the gas and the coating break down with usage, the smallest bulbs (T5) should start dimming sooner than the other ones. And since they have less gas and coating, they should give less light, when new, than same length T8 or T12. There are some High Output or Long Live bulbs that use the same technology but more expensive gas and coating. These differ from one bulb manufacturer to another.

I was in charge of lighting in the building of a previous employer. My experience on my job, where part of the building had the same type of lamps, some using T5s and other T8s, was that the T5 bulb lamps are generally dimmer than the same lamp with T8 bulbs. The difference becomes easily noticeable with bulbs that are couple of years old. There are also unbelievably obvious differences in quality between bulb manufacturers.

Ballasts: (control bulbs)
The electronic ballasts do make a huge difference in lifetime of the bulbs. They usually make less noise. The electronic ballasts themselves have limited lifetime. They’re quite often hard to replace so you have to replace the whole lamp should the ballast break down.

Lamps: (direct light from bulbs to objects)
Lamps have different characteristics and each has huge effect on the efficiency of the lighting. For hanging or ceiling lamps. Lighting that is directed straight down is most efficient but “softer” lighting that is reflected down from ceilings has positive effect on peoples moods and health.

Leds: (create visible light)
Have no ballasts, as such, but often have electronic circuits to control the light.

well this sure is timely. we’re building out a new shop and have been dealing with this exact issue. using T12s to light the shop right now, but also went out and bought a little T5 fixture for the special garden plants. interesting learning more than just ‘T5 is brighter’.

@ helgi
overall you’re a little off, macona and John nailed it though. the smaller lamps are (in theory) made to higher manufacturing tolerances with more precise and particular phosphors in them, so your assessment of t12 v t8 v t5 while anecdotal, is incorrect.

industry standard terms are:

lamp: the chunk of stuff that produces light, be it the LED diode, or the florescent tube, and any stuff that comes along with it as one unit. i.e. in CFLs the “lamp” includes the ballast, as the whole package screws into the fixture.

ballast: the widget between power source and lamp that gets the power to the lamp in a way that makes it illuminate properly in lamps that require a “strike”, not to be confused with dimmer, power supply, or driver, which vary the power supplied to vary light out put via a variety of measures. you can have a dimming ballast, but that does not make it a dimmer.

fixture: the thing you shove the lamp into, which holds the lamp where you want it, which may or may not have the ballast, or other things included in it.

@Metis.
I may not have the English name 100% correct but I still say that T5, T8 and T12 all work in exactly the same way and smaller bulbs (lamps) last for shorter periods before becoming dimmer. :D
I also say that the difference between same size bulbs (lamps) between different manufacturers is huge.
And if the electronic ballast breaks down, which happens a lot more often than the old style “brick” ballast and separate starter, you often have to replace the whole lamp (fixture). I’ve often had to replace electronic ballasts in lamps (fixtures) that were only couple of years old.

I have replaced bulbs a few times myself. The main thing to consider at all times is how close to pure sunlight is the output of the fl bulb. The ones which do have better purer output have always been available but at a slightly higher cost. They aren’t quite 6500K’s but dern close. Regardless of the fixture (not the ballast of course) these are well worth it, easier on the eyes, and have a notably improved output. If you call the right people, all the manufacturers can & will mail you a complete bulb catalogue-phillips, ge, sanyo etc. The objective of any std light source is to try and mimic sunlight. All else is pie in the sky.